This invention relates to a manually operated reciprocating fluid pump for dispensing lotions and other liquids.
A conventional reciprocating liquid pump for a lotion-type dispenser typically includes a plunger with a dispensing head that is manually reciprocated downwardly into a pump housing connected to a liquid container, a spring for biasing the plunger upwardly out of the pump housing, a priming valve, and a check valve. The priming valve unseats (opens) on the downward movement of the plunger into the pump housing to allow air in the empty pump housing to escape through the plunger and dispensing head, and then seats (closes) on the return stroke of the plunger upwardly out of the pump housing to draw liquid in the container up into the pump housing. The check valve seats on the downward movement of the plunger to prevent air or any liquid contained in the pump housing from being forced back into the container, and then unseats on the upward movement of the plunger to allow the vacuum created in the pump housing by the plunger's upward movement to draw liquid from the container past the check valve into the pump housing.
Often, ball valves are used for both the priming valve and check valve in manually reciprocated liquid pumps. However, ball valves typically require inwardly directed protrusions or some other type of stop to prevent the ball from traveling too far away from the valve seat. Such protrusions and stops are difficult to mold and increase the cost of manufacture. Also, when gritty product is the fluid to be dispensed, it often prevents a ball valve from seating properly against the valve seat, thereby reducing the effectiveness of the dispenser. Another disadvantage of ball valves is that the functioning of ball valves is dependent on gravitational forces which direct the ball of the valve downwardly to its seated position. If a liquid container having a reciprocating pump with ball valves is moved from its upright orientation, e.g., if it is placed on its side or inverted during shipment, gravity no longer seats the ball valves and the liquid in the container can pass through and leak from the pump.